PRACTICE EXAM
NAME__________________________________________
(45MINUTES MAXIMUM)
Using the fact that pK a
(HF) = 3.17; show THREE ways to construct a BUFFER solution at pH=3.17 using the following:
0.50M solution of NaOH
0.25M solution of NaF
0.50M solution of HCl
0.25M solution of NaCl
0.50M solution of HF
What is the pH of an aqueous solution of 0.754 M pyridine (a weak base with the formula
C
5
H
5
N) pK b
= 8.79
9.48 8.92 4.47 9.54 none
What concentration of Calcium hydroxide (assume STRONG and it all dissolves) is needed to give an aqueous solution with a pH of 10.730
2.69x10-4 5.37x10-4 1.34x10-4 3.27x10-4 none
If the pH of a solution of NaF is adjusted for pH. Using the fact that pK a
(HF) = 3.17; at what pH is 85% of the total fluoride in the form of F
-
?
3.17 3.92 2.42 3.99 none

Which of the following aqueous solutions are good buffer systems ?
0.18 M hydrocyanic acid + 0.19 M sodium acetate
0.24 M hydrobromic acid + 0.22 M potassium bromide
0.04 M sodium fluoride + 0.47 M hydrofluoric acid
0.31 M ammonia + 0.34 M amonium chloride
0.36 M potassium bromide + 0.26 M barium bromide
What is the pH of a solution contains 0.482 M ammonium iodide and 0.589 M ammonia.
(pK b
(NH
3
)= 4.75)
4.66 4.83 9.34 9.56 3.94
A buffer solution contains 0.481 M nitrous acid and 0.314 M sodium nitrite. K a
= 4.50 x 10
-4
If 0.0309 moles of sodium hydroxide are added to 250 ml of this buffer, what is the pH of the resulting solution?
3.91 1.56 3.16 3.43 4.33
What is the Hydroxide ion concentration of an aqueous solution of 0.541
M trIpropanolamine (a weak base with the formula (HOC
3
H
6
)
3
N)? K b
= 4.80x10
-8
2.50x10-8 1.61x10-4 3.85x10-7 6.21x10-11 none
What is the pH of a solution contains 0.202 M methylamine iodide and 0.389 M methylamine.
(pK b
(CH
3
NH
2
)= 3.37)
10.35 3.65 3.09 10.91 10.60 6.74

200ml of 0.481 M nitrous acid (pK a
= 3.35) ; 100 ml of 0.314 M sodium nitrite and 100 ml of
0.3M sodium hydroxide are mixed together , what is the pH of the resulting solution?
2.86 11.14 3.32 3.11 3.84 none
100ml of 0.25M Potassium Hydroxide is titrated to equivalence with 0.35M Sulfuric Acid, what volume is required and what will be the final pH?
0.20 M
ACID
0.30 M
BASE
50 ml
Chloroacetic
Acid
(pKa=2.85)
15 ml
Ca(OH)
2
1.90 3.80 3.34 2.76 2.80
50 ml HCl
50 ml NH3
(pK b
=4.75)
5.05 8.95 9.55 9.43 9.07 8.25